Light sources adapted to spectral sensitivity of diurnal avians and humans

ABSTRACT

Various apparatus and associated methods involve a light source that provides light at wavelengths that substantially correlate to local maxima in the spectral sensitivity of a diurnal avian. In an illustrative example, the light source may output light primarily in wavelength bands that are not substantially absorbed by colored oil droplets and/or visual pigment in at least one type of cone in the eye of a diurnal avian. In some embodiments, the light source may include a light-emitting diode (LED) light source. Exemplary light sources may output spectral components to illuminate diurnal avians with local maxima of intensity at wavelengths that substantially correspond to local maxima in a spectral sensitivity visual response characteristic of the diurnal avians.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/050,910 entitled “Light Sources Adapted to Spectral Sensitivity ofDiurnal Avians” to Grajcar and filed Mar. 17, 2011 that claims priorityto and the benefits of U.S. Provisional Patent Application entitled“Light Sources Adapted to Spectral Sensitivity of Diurnal Avians,” Ser.No. 61/314,617, which was filed by Z. Grajcar on Mar. 17, 2010, and U.S.Provisional Patent Application entitled “Dimmable LED Light EngineAdapted to Spectral Sensitivity of Diurnal Avians and Humans,” Ser. No.61/314,761, which was filed by Z. Grajcar on Mar. 17, 2010, the entirecontents of each of which are incorporated herein by reference.

TECHNICAL FIELD

Various embodiments relate generally to methods and apparatus involvinglight sources with spectral energy adapted based on light absorbanceresponse of a target avian and humans.

BACKGROUND

Lighting can be an important consideration in some applications, such aslivestock production. For example, incandescent or fluorescent lightsmay be turned on and off to simulate night and day for fowl livingindoors. So-called “long day” lighting practices have been proposed topromote increased daily milk production from cows. Some research alsosuggests, for example, that poultry development behaviors can beinfluenced by lighting intensity, color, or time schedule. For example,infrared lighting may promote aggression in chickens, while too muchdarkness might lead to fearfulness.

In general, “poultry” can refer to domesticated fowl raised for meat oreggs. Typical examples of poultry can include chickens, turkeys, ducks,geese, emus, ostriches or game birds. In some cases, poultry are raisedin a poultry house. An example poultry house could be 40 feet wide and600 feet long, with a ceiling that is eleven feet high. For so-called“broilers,” young chickens raised for their meat, one research studyfound that a schedule of intermittent lighting resulted in decreased fatdeposition and improved feed conversion efficiency relative to acontinuous lighting environment. (See Rahmi, G., et al., “The Effect ofIntermittent Lighting Schedule on Broiler Performance,” Int'l. J.Poultry Sci. 4 (6): 396-398 (2005)).

Various types of lighting have been employed in livestock productionfacilities. Livestock lighting systems that have been used includeincandescent, fluorescent, and more recently, LEDs (light emittingdiodes).

In general animal's perception of light involves photoreceptor cellsthat may be responsive to photons associated with light energy.Photoreceptors may be located in a retina. Photoreceptor cells may be ofa rod or cone type. Some cones may be less sensitive to light than rodcells, but cones may allow perception of color.

SUMMARY

Various apparatus and associated methods involve a light source thatprovides light at wavelengths that substantially correlate to localmaxima in the spectral sensitivity of a diurnal avian. In anillustrative example, the light source may output light primarily inwavelength bands that are not substantially absorbed by colored oildroplets and/or visual pigment in at least one type of cone in the eyeof a diurnal avian. In some embodiments, the light source may include alight-emitting diode (LED) light source. Exemplary light sources mayoutput spectral components to illuminate diurnal avians with localmaxima of intensity at wavelengths that substantially correspond tolocal maxima in a spectral sensitivity visual response characteristic ofthe diurnal avians.

Various apparatus and associated methods may further involve use of alight source to adjust the intensities of two sets of wavelengths atsubstantially different rates as a function of electrical inputexcitation level, while maintaining a substantially white appearance asperceived by a human. In an illustrative example, as input excitation isreduced, the light source may appear to a human spectral sensitivitycharacteristic to remain substantially white, with a slight shift inhue. As the input excitation is reduced, the light source maysimultaneously appears to significantly shift color temperature as itmay be perceived by the spectral sensitivity characteristic of a diurnalavian.

Various embodiments may achieve one or more advantages. For example,some embodiments may improve the welfare and/or lifetime development ofavians by stimulation with selected wavelengths tailored to the avian'snatural physiology. Some implementations may further provide sufficientillumination perceived by humans who may be working in lighted areas. Inpoultry lighting applications, for example, the LED source may be drivenat substantially high excitation to promote healthy growth at earlystages of bird development, and gradually dimmed and color-shifted overthe bird's life to promote selected behaviors. In some examples, anavian may perceive a rapid reduction in red and a proportionally smallreduction in green or blue as may be desirable for broilers, forexample. In some examples, an avian may perceive a rapid reduction inblue and a proportionally smaller reduction in green or red as may bedesirable for breeder production, for example. Energy efficiency may beenhanced by selecting wavelengths to reduce energy supplied atwavelengths that are not absorbed or useful to the avian. Variousembodiments may advantageously permit smooth, time-controlledturn-on/turn-off and incremental intensity adjustments that may minimizestress or simulate natural transitions of the sun, for example.

The details of various embodiments are set forth in the accompanyingdrawings and the description below. Other features and advantages willbe apparent from the description and drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an exemplary lighting installation in a facility fordiurnal avians.

FIG. 2A shows exemplary plots of spectral sensitivity as a function ofwavelength for humans and for chickens.

FIG. 2B illustrates exemplary plots of spectral absorbance for fourtypes of oil droplets found in some diurnal avian photoreceptor cells.

FIGS. 3-5 depict spectral content of exemplary incandescent,fluorescent, and light emitting diode (LED) sources, respectively.

FIG. 6 depicts a characteristic for an exemplary composite sourceadapted to provide light energy at wavelengths that substantiallycorrelate to peaks in the spectral sensitivity of a chicken.

FIG. 7A depicts an exemplary implementation of a source to form acomposite source adapted to provide light energy at wavelengths thatsubstantially correlate to peaks in the spectral sensitivity of adiurnal avian.

FIG. 7B depicts an exemplary implementation of a source to form acomposite source adapted to provide light energy at wavelengths thatsubstantially correlate to peaks in the spectral sensitivity of adiurnal avian.

FIG. 7C depicts an exemplary implementation of a source to form acomposite source adapted to provide light energy at wavelengths thatsubstantially correlate to peaks in the spectral sensitivity of adiurnal avian.

FIG. 7D depicts an exemplary implementation of a source to form acomposite source adapted to provide light energy at wavelengths thatsubstantially correlate to peaks in the spectral sensitivity of adiurnal avian.

FIG. 8A shows exemplary architecture for implementing a composite sourcefrom a source.

FIG. 8B shows exemplary architecture for implementing a composite sourcefrom a source.

FIG. 8C shows exemplary architecture for implementing a composite sourcefrom a source.

FIG. 9 depicts an exemplary light source device adapted to substantiallymatch at least portions of the diurnal avian's spectral sensitivitycharacteristics.

FIG. 10 is a flowchart of an exemplary method to provide a compositesource adapted to provide light energy at wavelengths that substantiallycorrelate to peaks in the spectral sensitivity of a diurnal avian.

FIG. 11A shows a schematic of an exemplary conditioning circuit for anLED light engine with selective current diversion to bypass a group ofLEDs while AC input excitation is below a predetermined level, withspectral output to substantially match about three spectral sensitivitypeaks of a diurnal avian and appear substantially white to human vision.

FIG. 11B shows a schematic of an exemplary conditioning circuit for anLED light engine with selective current diversion to bypass a group ofLEDs while AC input excitation is below a predetermined level, withspectral output to substantially match about three spectral sensitivitypeaks of a diurnal avian and appear substantially white to human vision.

FIG. 12A shows a relative plot of human and chicken spectral sensitivitythat may be provided by the light engines described with reference toFIG. 11(A,B).

FIG. 12B shows a relative plot of human and chicken spectral sensitivitythat may be provided by the light engines described with reference toFIG. 11(A,B).

FIG. 12C shows a relative plot of human and chicken spectral sensitivitythat may be provided by the light engines described with reference toFIG. 11(A,B).

FIG. 13A illustrates an exemplary plot of light output from the RUN andBYPASS LEDs, and their combined total output, over a range of inputvoltage excitation.

FIG. 13B illustrates an exemplary plot of light output from the RUN andBYPASS LEDs, and their combined total output, over a range of inputvoltage excitation.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

FIG. 1 shows an exemplary lighting installation in an agriculturalfacility for diurnal avians. In this example, FIG. 1 depicts anexemplary poultry facility in which the lighting may provide lightenergy at wavelengths that substantially correlate to peaks in thespectral sensitivity of the poultry. Various embodiments mayadvantageously achieve improved energy savings by providing energyprimarily in wavelength bands that are not substantially absorbed bycolored oil droplets and/or visual pigment in at least one type of conein the eye of the poultry.

In the example depicted in FIG. 1, a facility 100 includes a circuitbreaker panel 105, a controller 110, an electrical distribution system115, and a number of LED lamp assemblies 120. A pair of conductors 125provide single phase AC power (e.g., 120-240 VAC, at 50-60 Hz) to thefacility from a utility transmission system. Upon entering the facility100, the AC power is routed through the breaker panel 105 to thecontroller 110. The controller 110 may be operated (e.g., under controlof a programmed processor, or manual input) to provide a controlledreduction of the AC excitation for transmission to the LED lampassemblies via the electrical distribution system 115. The LED lampassemblies 120 are located within the facility 100 to artificiallyilluminate the livestock residing in a livestock area.

The depicted LED lamp assemblies 120 are hanging from electrical cordsfrom an elevated portion of the facility's electrical distributionsystem 115. In some implementations, the LED lamp assemblies 120 may bemounted as fixtures to infrastructure or supports within the facility100. The LED lamp assemblies 120 may be located at one or moreelevations within the facility, for example, to provide a high bayand/or low bay lighting.

As will be described in further detail with reference to FIGS. 7-10, thelighting system may include one or more types of sources with anintermediate light output signal processed with appropriate wavelengthselective conversion to provide light output signals with energyprimarily in wavelengths that may be transmitted by the colored oildroplets and pigmentation filters of an avian's cone.

The controller 110 may controllably attenuate the AC excitation voltageand/or current supplied to the LED lamp assemblies 120. By way ofexample and not limitation, the controller 110 may function as a phasecontrolled dimmer with leading edge and/or trailing edge phase cutting,pulse width modulation, or amplitude modulation, for example. Exemplaryapproaches for modulating the AC excitation are described in furtherdetail, for example, at least with reference to FIG. 1 of U.S.Provisional Patent Application entitled “Architecture for High PowerFactor and Low Harmonic Distortion LED Lighting,” Ser. No. 61/255,491,which was filed by Z. Grajcar on Oct. 28, 2009, the entire contents ofwhich are incorporated herein by reference. The control may be manual orautomatically controlled, for example, to provide a desired timing andduration of light and dark cycles (with corresponding color shiftprovided by operation of examples of the LED light circuit engine).Examples of light systems that incorporate color shift for livestockdevelopment are described in further detail, for example, at least withreference to FIGS. 1 and 6C of U.S. Provisional Patent Applicationentitled “LED Lighting for Livestock Development,” Ser. No. 61/255,855,which was filed by Z. Grajcar on Oct. 29, 2009, the entire contents ofwhich are incorporated herein by reference.

In various examples, the controller 110 may include includes a phasecontrol module to control what portion of the AC excitation waveform issubstantially blocked from supply to a light engine, where less blockagemay correspond to increased excitation level. In other embodiments, theAC excitation may be modulated using one or more other techniques,either alone or in combination. For example, pulse-width modulation,alone or in combination with phase control, may be used to module the ACexcitation at modulation frequency that is substantially higher than thefundamental AC excitation frequency.

In some examples, modulation of the AC excitation signal may involve ade-energized mode in which substantially no excitation is applied to thelight engine. Accordingly, some implementations may include a disconnectswitch (e.g., solid state or mechanical relay) in combination with theexcitation modulation control (e.g., phase control module 130). Thedisconnect switch may be arranged in series to interrupt the supplyconnection of AC excitation to the light engine. A disconnect switch maybe included on the circuit breaker panel 105 that receives AC input froman electrical utility source and distributes the AC excitation to thelamp assemblies 120. In some examples, the disconnect switch may bearranged at a different node in the circuit than the node in the circuitbreaker panel 105. Some examples may include the disconnect switcharranged to respond to an automated input signal (e.g., from aprogrammable controller) and/or to the user input element being placedinto a predetermined position (e.g., moved to an end of travel position,pushed in to engage a switch, or the like).

In some implementations, the facility may be used to grow livestock suchas poultry, turkey, geese, swine, cows, horses, goats, or the like. Byway of example and not limitation, the lighting installation may be usedto promote the development of diurnal avians, such as turkeys, ducks,parrots, or chickens including breeders, broilers, or layers, forexample.

FIG. 2A shows an exemplary plot 200 of spectral sensitivity as afunction of wavelength for chickens in a curve 205 and for humans in acurve 210. An exemplary representation of a human's spectralsensitivity, the curve 210 appears approximately as a bell curve with asingle peak sensitivity at approximately 555 nm (green). Generally asreferred to herein, spectral sensitivity may be understood as areciprocal measure of the energy or power to provide a particular visualresponse.

In the depicted figure, the curve 205 provides an exemplaryrepresentation of a chicken's spectral sensitivity appears with peaksevident in wavelengths between 380 and 780 nm. In this example, a firstpeak occurs at about 380 nm, a second peak occurs at about 490 nm, athird peak occurs at about 560 nm, and a fourth peak occurs at about 630nm. These examples are illustrative and not limiting. Indeed, theamplitude and wavelength and each peak of spectral sensitivity may varyamong avian species, among individuals within a species, and for anindividual avian over time. For example, an individual diurnal avian mayadapt in response to exposure to a set of lighting conditions (e.g.,intensity and/or spectral content) by shifting its spectralresponsiveness in amplitude and wavelength over time. In some cases, thevisual pigmentation may adjust its consistency. In some cases, thenumber, density and/or distribution of photoreceptors of a particulartype may change over time, which may affect a change in an individualavian's spectral sensitivity over time.

According to the exemplary plots in FIG. 2A, chickens and humans havesimilar sensitivity to green colors (e.g., about 560 nm). Chickens havesubstantially higher sensitivity to green-blue-ultraviolet (e.g., belowabout 500 nm) and to orange-red (e.g., above about 600 nm to about 720nm).

By way of illustrative explanation, the tetra-chromatic spectralsensitivity of some diurnal avians may be further understood withreference to FIG. 2B.

FIG. 2B illustrates an exemplary plot 250 of spectral absorbance forfour types of oil droplets found in some diurnal avian photoreceptorcells. Unlike some other animals, some avians have photoreceptor conecells with colored (e.g., pigmented) oil droplets that filter incominglight. Research studies indicate that these oil droplets are highlyrefractive spherical organelles disposed in some avian cones between thevisual pigment and the incident light. As incident light enters the coneof a chicken eye, for example, a colored oil droplet may spectrallyfilter the light before it reaches the visual pigment. The combinedspectral filtering effect of the colored oil droplet and visual pigmentmay substantially attenuate certain wavelengths, or a band ofwavelengths, of the incoming light. Some birds have four types of conesthat exhibit different wavelength selective responses. These absorbancecharacteristics indicate a degree to which incident light will beattenuated as a function of the incident light's wavelength. In anindividual cone, with an oil droplet with one of the four depictedabsorbance characteristics, light with wavelengths substantially outsideof the “bandwidth” of the characteristic may be transmittedsubstantially without attenuation to a visual pigment element in thecone.

By way of further background as helpful explanation, and not intended toas a limitation, chicken eyes may include four photo-reactive pigmentsassociated with cone cells that provide photopic vision. In contrast,human eye cones have only three pigments. While the human istrichromatic with three pigments, some diurnal avians, such as chickens,may be tetra-chromatic with four pigments.

It is believed that the sensitivity of a particular avian to aparticular wavelength is, in part, a function of the number of conesthat pass that particular wavelength. Density and distribution of conesof a particular type may thus affect the corresponding sensitivity ofthe avian to a range of amplitudes of light at any given wavelength.

In some examples, the selective wavelength converter (SWC) may includequantum dots in the optical path. When applied as a film to a die or alens, for example, the quantum dot material may absorb some of light atone wavelength (e.g., cool blue) and re-emit the light at asubstantially different wavelength (e.g., warm red). Accordingly, anoptimal spectral output may be pursued by selecting a narrowband sourceof a first wavelength in conjunction with wavelength selectiveconversion using quantum dots. Appropriate selection of source andconversion media may advantageously yield a spectral output with energyat one or more wavelengths that each correspond to a peak of the avianspectral sensitivity. Examples of quantum dots are commerciallyavailable from QDVision of Massachusetts.

Diurnal avians include, for example, various galliformes (an order ofbirds that may include turkeys, grouse, chickens, quails, and pheasants)bird species, which are believed to have among the most complex retinaeof any vertebrate.

Retinae of diurnal (e.g., active during day) birds may include a singleclass of medium wavelength sensitive (MWS) rod, and four classes ofsingle cone with maximum sensitivities to different regions of thespectrum. The single cones may include oil droplets at the distal end oftheir inner segments. Oil droplets are highly refractive sphericalorganelles located in the photoreceptor between the visual pigment andthe incident light. In all but one of the single cone types, the oildroplets contain short-wavelength absorbing carotenoid pigments thatspectrally filter the incident light before it reaches the visualpigment in the outer segments. Pigmented oil droplets act as long-passcutoff filters and shift the effective sensitivity peak of the cone to awavelength longer than the long wavelength portion of the passband ofthe visual pigment contained in the outer segment. They also narrow thespectral sensitivity function of the cone.

In addition to the retinal photoreceptors in the eye, some species haveother photoreceptors that may contribute to the overall spectralsensitivity. For example, some species (e.g., chicken) have dorsalphotoreceptors oriented in a generally skyward direction when the avianis standing erect. A lighting system may specifically target dorsalphotoreceptors with directional (e.g., beam pattern) lighting fromabove, for example.

FIGS. 3-5 depict spectral content of exemplary incandescent,fluorescent, and light emitting diode (LED) sources, respectively. Theoutput spectra of these sources are individually overlaid on therelative spectral sensitivity characteristics as described withreference to FIG. 2A.

FIG. 3 depicts a plot of an incandescent spectrum 300. Curve 305reflects an experimentally measured spectral characteristic for a 60Watt DOUBLE LIFE™ incandescent bulb, commercially available from GeneralElectric.

FIG. 4 depicts a plot of an incandescent spectrum 400. Curve 405reflects an experimentally measured spectral characteristic for a 23Watt SLS-23 fluorescent bulb, commercially available from PhilipsLighting Company of New Jersey.

FIG. 5 depicts a plot of an incandescent spectrum. Curve 505 reflects anexperimentally measured spectral characteristic for an arrangement ofhigh power 1 W LEDs, model EHP-A21/GT46H-P01/TR, commercially availablefrom Everlight Electronics Co., Ltd. of Taiwan.

FIG. 6 depicts a characteristic for an exemplary composite sourceadapted to provide light energy at wavelengths that substantiallycorrelate to peaks in the spectral sensitivity of a chicken. A plot 600indicates relative intensity as a function of wavelength (nm) for: adomestic fowl relative eye response curve 605, an exemplary compositesource 610, a curve 615 representing what the domestic fowl perceivesfrom the composite source. Exemplary implementations that may yield thedepicted source spectral output 610 are described with reference toFIGS. 7-8.

In an illustrative example, the curve 615 represents an exemplarycharacteristic visual response to the composite light source spectrum asperceived by the chicken 615. The visual response characteristic is afunction of the spectral sensitivity to the light source at eachwavelength, and the sensitivity of the chicken at the correspondingwavelength.

In particular, the depicted light source characteristic curve 610 haspeak of intensity at about 480 nm. A pass band (e.g., between about460-500 nm) associated with this peak represents energy that issubstantially within the bandwidth of the second peak of the chickenspectral sensitivity around about 500 nm, which has an approximatebandwidth that may be considered to include at least between about450-520 nm. Similarly, the composite source includes peaks that liesubstantially within a bandwidth of the chicken's spectral sensitivitypeaks at about 560 nm and about 630 nm, respectively.

Moreover, the composite source exhibits relatively low energy content,or local minima of intensity, at wavelengths that substantiallycorrespond to local minima of the chicken's spectral sensitivity. In thedepicted example, the composite source may be seen to have substantiallyminimal or local intensity minima at corresponding sensitivity minima(e.g., about 410 nm, 510 nm, 605 nm, or above about 680 nm in thisexample).

FIG. 7 depicts exemplary implementations of sources to form a compositesource adapted to provide light energy at wavelengths that substantiallycorrelate to peaks in the spectral sensitivity of a diurnal avian. Eachimplementation may be formed from a combination of one or more types ofsources, including, but not necessarily limited to, the sourcesdescribed with reference to FIGS. 3-5. Some composite sources mayfurther include metal halide, high pressure sodium, or other highintensity discharge source. A composite source may be formed of a singletype of source, alone or in combination with one or more sources, toobtain a composite source adapted to provide light energy at wavelengthsthat substantially correlate to peaks in a spectral sensitivity of aspecified diurnal avian.

FIGS. 7 a-7 d depict exemplary networks of two or more sources A-L toform a composite source. In some examples, each of the sources A-L mayeach individually include a network that includes one or more elementsof a single type of source (e.g., at least one fluorescent bulb, anetwork of one or more LEDs, an array of incandescent bulbs). Eachnetwork may include sources having selected wavelength output spectra toachieve the specified composite output that substantially matches atleast portions of the diurnal avian's spectral sensitivitycharacteristics. Some exemplary networks may include two or moreelements of the same source type arranged in series, parallel, and/orcombinations of series and parallel, including two or more parallelbranches. In FIG. 7 a, for example, the same excitation current flowsthrough both of the sources A,B, and the excitation may be either AC orDC. In FIG. 7 b, for example, sources J and K-L are independent branchesthat may be independently excited with different voltage and/or current,and the excitation to either branch may be either AC or DC.

FIG. 8 shows exemplary architectures for implementing a composite sourcefrom various sources.

In FIG. 8 a, a wideband source supplies a light signal to be processedby a selective wavelength converter (SWC). The SWC processes the lightsignal from the wideband light source using apparatus or techniques tosubstantially shift energy content at one or more selected wavelengthsto different wavelengths. By appropriate selection of source and SWC, acomposite source may be created to output light at wavelengths thatsubstantially match a diurnal avian's spectral characteristic.

In some embodiments, the selective wavelength converter (SWC) mayinclude quantum dots in the optical path, as described with reference toFIG. 2B.

In some other embodiments, the SWC may include a phosphor-like materialthat emits light at one wavelength in response to stimulation at adifferent wavelength.

In some examples, the composite source may use, for example, a number ofincandescent bulbs arranged in series as a substantially widebandsource. A film of quantum dots and/or phosphors may be provided in theoptical path of the LED output to shift some energy, for example, from ared spectrum to a green and/or a blue portion of the spectrum. Theresulting output of the composite source may substantially match (e.g.,lie substantially within the pass band of) at least three of the peaksand at least two local minima of the diurnal avian's spectralsensitivity response characteristic.

FIG. 8 b depicts an exemplary composite sourced formed by threeindependent monochromatic sources. For example, a network of green, red,and blue LEDs may output arranged in a network (e.g., in accordance withany of FIGS. 7 a-7 d) combined light signal that substantially matches asensitivity spectral characteristic of a chicken.

FIG. 8 c depicts an exemplary composite sourced formed by a white sourceand two independent monochromatic sources in conjunction with a SWC. Forexample, a network of cool white LEDs may serve as the “white” source,and red and/or blue LEDs may serve as the two monochromatic sources. TheSWC may shift at least some energy in order to provide peaks of thecomposite light source intensity that fall substantially within a passband of at least 2 of the peaks of the avian spectral sensitivitycharacteristic.

FIG. 9 depicts an exemplary light source device adapted to substantiallymatch at least portions of the diurnal avian's spectral sensitivitycharacteristics. In this figure, an illuminant substrate outputs a firstset of wavelengths that are directed generally upward from a top surfaceof the illuminant. The illuminant may include one or more units of asource (e.g., one or more LEDs, fluorescent elements, incandescentelements).

The first set of wavelengths pass through a SWC provided as a film orlayer in the optical path. The SWC may be implemented in variousembodiments as described above, including quantum dots, phosphors, or acombination thereof. The spectral content of the light emitted by theSWC has at least some energy at wavelengths that have shifted withrespect to the spectral content emitted by the illuminant. The opticalpath in this example further includes a lens, which may or may notincorporate another SWC element to further tailor the spectral contentof the composite source to more accurately match the spectralsensitivity characteristic of the avian.

FIG. 10 is a flowchart of an exemplary method to provide a compositesource adapted to provide light energy at wavelengths that substantiallycorrelate to peaks in the spectral sensitivity of a diurnal avian. Themethod 1000 may be implemented by a processor executing operationsaccording to a set of instructions retrieved from a data store. Some orall of the steps of the method may be implemented by at least oneprocessor that is included in at least one computer, such as a desktop,laptop, server, or portable digital device.

When started at step 1005, the method 1000 includes a step 1010 forinitializing an index (n) to one. Then, at step 1015, the processorselects a wavelength for the index at which there is a local peak insensitivity based on a spectrum of the target avian's oil dropletabsorbance and visual pigmentation. In some embodiments, oil dropletabsorbance information and information about spectral transmissionthrough visual pigments for a particular species of diurnal avian may bestored as records in a data store. If there are more peaks of thesensitivity to identify at step 1020, then the index increments and thewavelength selection step 1015 is repeated.

When all the peaks have been identified, at step 1030 the maximum numberof peaks is stored (nmax), and the index is reset to one. Then, theprocessor performs operations to select a source to supply illuminationat the wavelength for the index at step 1035.

If, at step 1040, a selective wavelength conversion is required to matchthe source wavelength spectrum to the selected wavelength at the index,then the processor performs operations at step 1045 to select aselective wavelength converter (SWC) suitable to convert the selectedsource to the selected wavelength for the index. For example, the SWCmay be a phosphor alone or in combination with a film of quantum dots.

If the index has not reached nmax at step 1050, then the indexincrements at step 1055 and the source selection step 1035 is repeated.When all the selected peaks have been associated with a source and anyrequired SWC, the method ends at step 1060.

FIG. 11 shows schematics of exemplary conditioning circuits for an LEDlight engine with selective current diversion to bypass a group of LEDswhile AC input excitation is below a predetermined level, with spectraloutput to substantially match about three spectral sensitivity peaks ofa diurnal avian and appear substantially white to human vision. Inparticular, the combination of LED outputs may provide a spectral energythat substantially matches a spectral sensitivity of a selected diurnalavian. In some embodiments, the LED output spectrum may be provided byan LED (or combination of LEDs) in combination with a selectivewavelength converter (SWC), examples of which are described withreference, for example, at least to FIGS. 8-10 of U.S. ProvisionalPatent Application entitled “Light Sources Adapted to SpectralSensitivity of Diurnal Avians,” Ser. No. 61/314,617, which was filed byZ. Grajcar on Mar. 17, 2010, the entire contents of which areincorporated herein by reference.

FIG. 11( a) depicts 40 white and 12 red LEDs in a first group betweennodes A,C, referred to herein as the “RUN” group of LEDs, and with 10blue LEDs in a second group between nodes C, B, referred to herein asthe “BYPASS” group of LEDs.

FIG. 11( b) depicts 48 white and 6 blue LEDs in the “RUN” group, and 20red LEDs in the “BYPASS” group.

As depicted, the exemplary light engine includes a circuit excited by anAC (e.g., substantially sinusoidal) voltage source V1. The AC excitationfrom the source V1 is rectified by diodes D1-D4. A positive output ofthe rectifier, at node A, supplies rectified current to a first set ofLEDs, LED1-LED54, (RUN LEDs) which are connected as a network of twoparallel strings from node A to node C.

At node C, current may divide between a first path through a second setof LEDs and a second path through a current diversion circuit. The firstpath from node C flows through the second set of LEDs, LED55-LED74,(BYPASS LEDs) to a node B, and then on through a series resistance, R1and R2. In some embodiments, a peak current drawn from source V1 maydepend substantially on the series resistance R1 and R2.

The second path from node C flows through a selective current diversioncircuit that includes Q1, Q2, R3, and R4. In some examples, the currentdrawn from the source V1 at intermediate excitation levels may dependsubstantially on the selective current diversion circuit.

In some embodiments, the schematics of FIG. 11( a,b) may be modified toarrange LEDs in different series and/or parallel networks. For example,the RUN group in FIG. 11( a) may include three or more branches of LEDsred and/or white LEDs. In another example, the RUN group in FIG. 11( b)may include one or more blue and/or white LEDs in a serial and/orparallel network examples that is itself in series with the depictedparallel network. In another embodiment, the BYPASS group of LEDS mayinclude additional LEDs to tailor the spectral output, such as a numberof white (e.g., cool white) LED sources.

The RUN and BYPASS groups of LED1-LED74 may be in a single module suchas a hybrid circuit module or assembly. In some examples, the LEDs LED1-LED74 may be arranged as individual or discrete packages and/or ingroups of LEDs. The individual LEDs may output all the same colorspectrum in some examples. In other examples, one or more of the LEDsmay output substantially different colors than the remaining LEDs.Various embodiments may utilize inexpensive low CRI (color renderingindex) LEDs

The number of LEDs is exemplary, and is not meant as limiting. Forexample, the number of red or blue LEDs may be 1, 2, 3, 4, 5, 6, 7, 8,9, 10, 11, 12, 13, 14, 15, 16, 20, 24, or at least 30 or more, foroperation on 120 VAC excitation, and may be further adjusted accordingto brightness, spectral content, other LEDs in the circuit, circuitarrangement (e.g., 2 or more parallel branches) and/or LED forwardvoltage, for example. The number of white LEDs may be increased usingthe depicted arrangement to include from about 18 to about 38 whiteLEDs, such as between about 21 to 27 LEDS.

The number of LEDs may be designed according to the forward voltage dropof the selected LEDs and the applied excitation amplitude supplied fromthe source V1. The number of LEDs in the first set between nodes A, Cmay be reduced to achieve an improved power factor. The LEDs betweennodes A, C may be advantageously placed in parallel to substantiallybalance the loading of the two sets of LEDs according to their relativeduty cycle, for example. In some implementations, current may flowthrough the RUN LED group whenever input current is being drawn from thesource V1, while the current through the BYPASS LED group may flowsubstantially only above a threshold voltage excitation from the sourceV1.

Suitable LEDs may be selected according to their color output to createa combine spectral output in accordance, for example, with the exemplaryspectra described with reference to FIG. 12. By way of example, and notlimitation, a representative example of suitable LEDs may include modelsEHP-A21/UB01H-P01/TR or EHP-A21/GT46H-P01/TR, which are commerciallyavailable from Everlight Electronics Co., Ltd. of Taiwan; modelsSLHNNWW629T00S0S373 or SPMRED3215A0AEFCSC, which are commerciallyavailable from Samsung LED Co., LTD. of Korea.

The spectral output of one or more of the LEDs may be tailored byconverting energy from one wavelength to a different wavelength, forexample, using selective wavelength conversion (SWC) techniques.Examples of SWC techniques using phosphors or quantum dots are describedin further detail with reference to at least FIGS. 8-9 of U.S. Ser. No.61/314,617.

FIG. 12 shows relative plots of human and chicken spectral sensitivitythat may be provided by the light engines described with reference toFIG. 11( a,b). The exemplary human characteristic spectral sensitivitycurve 1220 (e.g., bell curve shape plot) and an exemplary chickenpredetermined characteristic spectral sensitivity curve 1205 (3 peaksbetween 400-680 nm) depict spectral sensitivities shown in dashed lines,examples of which are discussed in further detail with reference to atleast FIG. 12A of U.S. Ser. No. 61/314,617.

FIG. 12( a) depicts that an exemplary intensity plot 1210 for anexemplary light engine at a first intensity level, which may beconsidered here to be 100% full intensity for purposes of illustration.A chicken visual response curve 1215 and a human visual response curve1225 depict the respective responses to the light source curve 1210. Thelight engine output may be produced, for example, by either of thecircuits of FIG. 11( a,b) operating at full intensity.

In this illustrative example, the human visual response generallymatches the shape and bandwidth of the bell curve for the human spectralsensitivity characteristic.

The chicken's visual response extends to wavelengths above and below the“pass band” of the human characteristic. The chicken visual responsepeaks around wavelengths at which the chicken spectral sensitivity andthe LED light source have their local maxima (e.g., around 480 nm, 560nm, and 600 nm).

FIG. 12( b) represents exemplary intensity plots for a light engine,including the circuit of FIG. 11( a), at a first reduced intensitylevel, which may be considered here to be 40% full intensity forpurposes of illustration. The chicken 1215 and human 1225 visualresponses to this light source 1210 are also plotted. The light engineoutput may be produced by the circuit of FIG. 11( a) operating at about40% intensity (e.g., a reduced input excitation voltage level).

FIG. 12( b) illustrates that LED source intensity has a differentspectral profile than FIG. 12( a). In particular, blue colors (e.g.,wavelengths below 470 nm) associated with the blue LEDs in the BYPASSLED group are substantially more attenuated than the intensity of redcolors (e.g., wavelengths above about 620 nm) associated with the redLEDs in the RUN group of FIG. 1(a). The different rates of attenuationmay be accounted for by the conditioning operations of the selectivediversion circuitry.

In response to the light source spectral profile of FIG. 12( b), thehuman visual response generally matches the shape and bandwidth of thebell curve for the human spectral sensitivity characteristic. As such, atypical human may perceive the light as dimmer, but still with theappearance of white light with reasonably good color rendering. Thehuman perception may be considered to be substantially white with aslight reddish hue.

The chicken's visual response to the source includes substantiallyreduced perception of most blue color, while maintaining substantialgreen and red, albeit at a partially reduced intensity compared to FIG.12( a). As an illustrative example, this reddish color mayadvantageously conserve energy otherwise supplied in the blue spectrum,while being perceived by the chicken as reasonably bright illuminationwith red content that may, according to some research, promote breedingactivities.

As such, the circuit of FIG. 11( a) may be advantageous as a highlyefficient lighting system tailored for breeder chickens, for example.Even though the chicken perceives a substantial color shift towards thered spectrum and away from blue, embodiments of the circuit of FIG. 11(a) may further be advantageous as a light to permit humans to see withgood color rendering over a wide dimming range.

FIG. 12( c) represents exemplary intensity plots for a light engine,including the circuit of FIG. 11( b), at a first reduced intensitylevel, which may be considered here to be 40% full intensity forpurposes of illustration. The chicken 1215 and human 1225 visualresponses to this light source 1210 are also plotted. The light engineoutput may be produced by the circuit of FIG. 11( b) operating at about40% intensity (e.g., a reduced input excitation voltage level).

FIG. 12( c) illustrates that LED source intensity has a differentspectral profile than FIG. 12( a). In particular, red colors associatedwith the red LEDs in the BYPASS LED group are substantially moreattenuated than the intensity of blue colors associated with the blueand/or cool white LEDs in the RUN group of FIG. 11( b). The differentrates of attenuation may be accounted for by the conditioning operationsof the selective diversion circuitry.

In response to the light source spectral profile of FIG. 12( c), thehuman visual response generally matches the shape and bandwidth of thebell curve for the human spectral sensitivity characteristic. As such, atypical human may perceive the light as dimmer, but still with theappearance of white light with reasonably good color rendering. Thehuman perception may be considered to be substantially white with aslight bluish hue (e.g., due to a small peak around 480 nm in thisexample).

The chicken's visual response to the source includes substantiallyreduced perception of most red color, while maintaining substantialgreen and blue, albeit at a lower intensity compared to FIG. 12( a). Asan illustrative example, this bluish color may advantageously conserveenergy otherwise supplied in the red spectrum, while being perceived bythe chicken as reasonably bright illumination with blue-green contentthat may, according to some research, promote growth and non-aggressivebehaviors.

As such, the circuit of FIG. 11( b) may be advantageous as a highlyefficient lighting system tailored for broiler chickens, for example.Even though the chicken perceives a substantial color shift towards theblue spectrum and away from red, embodiments of the circuit of FIG. 11(b) may further be advantageous as a light source to permit humans to seewith good color rendering over a wide dimming range.

FIG. 13( a,b) illustrate exemplary plots 1300 of light output from theRUN 1305 and BYPASS 1310 LEDs, and their combined total output 1315,over a range of input voltage excitation.

FIG. 13( a) is a plot of exemplary light output in units of lumens foran example LED lamp with a circuit substantially similar to either ofthose of FIG. 11( a,b). As the AC r.m.s. voltage is increased to about45 volts, the RUN group of LEDs starts to conduct significant forwardcurrent and output light. The current from the RUN LEDs is divertedaround the BYPASS group of LEDs until the AC input excitation is furtherincreased to about 90 volts. As the voltage continues to increase, lightfrom the BYPASS LEDs add to the light from the RUN LEDs, causing thetotal light output to exceed the light output from the RUN LEDs alone.

FIG. 13( b) depicts the plot of FIG. 13( a) in terms of normalized lightoutput and percent of rated input excitation. In the depicted example,the total flux exhibits an inflection point at the point at which theBYPASS circuit begins to conduct current and output light.

Although various embodiments have been described with reference to thefigures, other embodiments are possible. For example, some embodimentsof a composite source may produce a maximum light intensity at awavelength that substantially corresponds to a maximum sensitivity ofthe diurnal avian's spectral sensitivity. In some examples, this mayadvantageously enhance an efficiency associated with visual responseperception and electrical energy input consumption. In some furtherembodiments, the composite source may produce a second highest lightintensity at a wavelength that substantially corresponds to a secondhighest sensitivity of the diurnal avian's spectral sensitivity. In someexamples, this may advantageously further enhance the efficiencyassociated with visual response perception and electrical energy inputconsumption.

In some implementations, a facility similar to the facility 100 of FIG.1, for example, may be used to grow livestock such as swine, cows,horses, goats, diurnal avians (e.g. chickens, turkeys), or the like. Byway of example and not limitation, the lighting may be used to promotethe development of chickens such as breeders, broilers, or layers, forexample. In various embodiments, the lighting may be sourced by one ormore LED lamps, each of which may output a color temperature that is afunction of the AC excitation level supplied from the controller. Fordifferent types of livestock, the color shift may be different tooptimize the light exposure for each type. For example, breeders mayrequire some periods of infrared light to promote sexual activity.Optimal spectral profiles may be developed based on published researchresults or empirical data, and appropriate spectral profiles may beprovided by appropriate selection of type, number and color of groups ofLEDs, LED light engine architecture with bypass circuitry, and dimmingcontrol profile.

One study found that the three pigments in cones of a human eye may havelocal sensitivity maxima, for example, at about 419, 531, and 558 nm(Dartnall et al., 1983). The study further indicates that the fourpigments in a chicken eye may have local sensitivity maxima, forexample, at about 415, 455, 508, and 571 nm.

Various spectral components may be advantageous for birds at differentstages of development. For example, research indicates that broilerchickens under blue or green light may become significantly heavier thansimilar chickens exposed to red or white light. (Rozenboim et al., 2004)Some research indicates that green light may accelerate muscle growth(Halevy et al., 1998) and may stimulate growth at an early age, whereasblue light may stimulate growth in older birds (Rozenboim et al., 999,2004). Some studies have found that young broilers have a strongpreference for bright light (Davis et al., 1997).

In some embodiments, materials selection and processing may becontrolled to manipulate the LED color temperature and other lightoutput parameters (e.g., intensity, direction) so as to provide LEDsthat will produce a desired composite spectral output. Appropriateselection of LEDs to provide a desired color temperature, in combinationwith appropriate application and threshold determination for the bypasscircuit, can advantageously permit tailoring of color temperaturevariation over a range of input excitation.

Some implementations may be controlled in response to signals fromanalog or digital components, which may be discrete, integrated, or acombination of each. Some embodiments may include programmed and/orprogrammable devices (e.g., PLAs, PLDs, ASICs, microcontroller,microprocessor, digital signal processor (DSP)), and may include one ormore data stores (e.g., cell, register, block, page) that provide singleor multi-level digital data storage capability, and which may bevolatile and/or non-volatile. Some control functions may be implementedin hardware, software, firmware, or a combination of any of them.

Computer program products may contain a set of instructions that, whenexecuted by a processor device, cause the processor to performprescribed functions. These functions may be performed in conjunctionwith controlled devices in operable communication with the processor.Computer program products, which may include software, may be stored ina data store tangibly embedded on a storage medium, such as anelectronic, magnetic, or rotating storage device, and may be fixed orremovable (e.g., hard disk, floppy disk, thumb drive, CD, DVD).

In some implementations, a computer program product may containinstructions that, when executed by a processor, cause the processor toadjust the color temperature and/or intensity of lighting, which mayinclude LED lighting. Color temperature may be manipulated by acomposite light apparatus that combines one or more LEDs of one or morecolor temperatures with one or more non-LED light sources, each having aunique color temperature and/or light output characteristic. By way ofexample and not limitation, multiple color temperature LEDs may becombined with one or more fluorescent, incandescent, halogen, and/ormercury lights sources to provide a desired color temperaturecharacteristic over a range of excitation conditions.

In accordance with another embodiment, AC input excitation may bemodified by other power processing circuitry. For example, a dimmermodule that uses phase-control to delay turn on and/or interrupt currentflow at selected points in each half cycle may be used. In some cases,harmonic improvement may still advantageously be achieved even whencurrent is distorted by the dimmer module. Improved power factor mayalso be achieved where the rectified sinusoidal voltage waveform isamplitude modulated by a dimmer module, variable transformer, orrheostat, for example. In some embodiments, electrical input excitationmay be substantially AC, DC (e.g., battery, rectifier, solar powered),or a combination thereof.

In one example, the excitation voltage may have a substantiallysinusoidal waveform, such as line voltage at about 120 VAC at 50 or 60Hz. In some examples, the excitation voltage may be a substantiallysinusoidal waveform that has been processed by a dimming circuit, suchas a phase-controlled switch that operates to delay turn on or tointerrupt turn off at a selected phase in each half cycle. In someexamples, the dimmer may modulate the amplitude of the AC sinusoidalvoltage (e.g., AC-to-AC converter), or modulate an amplitude of therectified sinusoidal waveform (e.g., DC-to-DC converter).

In some implementations, the amplitude of the excitation voltage may bemodulated, for example, by controlled switching of transformer taps. Ingeneral, some combinations of taps may be associated with a number ofdifferent turns ratios. For example, solid state or mechanical relaysmay be used to select from among a number of available taps on theprimary and/or secondary of a transformer so as to provide a turns rationearest to a desired AC excitation voltage.

In some examples, AC excitation amplitude may be dynamically adjusted bya variable transformer (e.g., variac) that can provide a smoothcontinuous adjustment of AC excitation voltage over an operating range.In some embodiments, AC excitation may be generated by a variablespeed/voltage electro-mechanical generator (e.g., diesel powered). Agenerator may be operated with controlled speed and/or currentparameters to supply a desired AC excitation to an LED-based lightengine, such as the light engine of FIG. 1, for example. In someimplementations, AC excitation to the light engine may be provided usingwell-known solid state and/or electro-mechanical methods that maycombine AC-DC rectification, DC-DC conversion (e.g., buck-boost, boost,buck, flyback), DC-AC inversion (e.g., half- or full-bridge, transformercoupled), and/or direct AC-AC conversion. Solid state switchingtechniques may use, for example, resonant (e.g., quasi-resonant,resonant), zero-cross (e.g., zero-current, zero-voltage) switchingtechniques, alone or in combination with appropriate modulationstrategies (e.g., pulse density, pulse width, pulse-skipping, demand, orthe like).

This document discloses technology relating to light sources adapted tospectral sensitivities of diurnal avians. Related exampleimplementations, techniques, or apparatus may be found inpreviously-filed disclosures that have common inventorship with thisdisclosure.

Examples of technology for dimming and color-shifting a light sourcewith AC excitation are described with reference, for example, to thevarious figures of U.S. Provisional Patent Application entitled “ColorTemperature Shift Control for Dimmable AC LED Lighting,” Ser. No.61/234,094, which was filed by Z. Grajcar on Aug. 14, 2009, the entirecontents of which are incorporated herein by reference.

Examples of technology for improved power factor and reduced harmonicdistortion for color-shifting a light source are described withreference, for example, at least to FIGS. 20A-20C of U.S. ProvisionalPatent Application entitled “Reduction of Harmonic Distortion for LEDLoads,” Ser. No. 61/233,829, which was filed by Z. Grajcar on Aug. 14,2009, the entire contents of which are incorporated herein by reference.

Further embodiments of light engines for a lighting system are describedwith reference, for example, at least to FIGS. 1, 2, 5-5B, 7A-7B, and10A-10B of U.S. Provisional Patent Application entitled “Architecturefor High Power Factor and Low Harmonic Distortion LED Lighting,” Ser.No. 61/255,491, which was filed by Z. Grajcar on Oct. 28, 2009, theentire contents of which are incorporated herein by reference.

Various embodiments may incorporate one or more electrical interfacesfor making electrical connection from the lighting apparatus to anexcitation source. An example of an electrical interface that may beused in some embodiments of a downlight is disclosed in further detailwith reference, for example, at least to FIG. 1-3, or 5 of U.S. Designpatent application entitled “Lamp Assembly,” Ser. No. 29/342,578, whichwas filed by Z. Grajcar on Oct. 27, 2009, the entire contents of whichare incorporated herein by reference.

Instead of a threaded screw-type interface, some embodiments may includea section of a track lighting-style receptacle to receive the dual postinterface of an exemplary lamp. For example, a dual post electricalinterface of the type used for GU 10 style lamps may be used. An exampleof an electrical interface that may be used in some embodiments of adownlight is disclosed in further detail with reference, for example, atleast to FIG. 1, 2, 3, or 5 of U.S. Design patent application entitled“Lamp Assembly,” Ser. No. 29/342,575, which was filed by Z. Grajcar onOct. 27, 2009, the entire contents of which are incorporated herein byreference.

Some embodiments of a light apparatus may be integrated with packagingand/or thermal management hardware. Examples of thermal or otherelements that may be advantageously integrated with the embodimentsdescribed herein are described with reference, for example, to FIG. 15in U.S. Publ. Application 2009/0185373 A1, filed by Z. Grajcar on Nov.19, 2008, the entire contents of which are incorporated herein byreference.

This document discloses technology relating to dimmable LED lightengines adapted to spectral sensitivities of diurnal avians and humans.Related example implementations, techniques, or apparatus may be foundin previously-filed disclosures that have common inventorship with thisdisclosure.

Various examples of apparatus and methods may relate to lighting forproviding light energy at wavelengths that substantially correlate topeaks in the spectral sensitivity of the poultry. Examples of suchapparatus and methods are described with reference, for example, atleast to FIGS. 2A-2B of U.S. Provisional Patent Application entitled“Light Sources Adapted to Spectral Sensitivity of Diurnal Avians,” Ser.No. 61/314,617, which was filed by Z. Grajcar on Mar. 17, 2010, theentire contents of which are incorporated herein by reference.

Various embodiments relate to dimmable lighting for livestock. Examplesof such apparatus and methods are described with reference, for example,at least to FIGS. 3, 5A-6C of U.S. Provisional Patent Applicationentitled “LED Lighting for Livestock Development,” Ser. No. 61/255,855,which was filed by Z. Grajcar on Oct. 29, 2009, the entire contents ofwhich are incorporated herein by reference.

Examples of technology for dimming and color-shifting a light sourcewith AC excitation are described with reference, for example, to thevarious figures of U.S. Provisional Patent Application entitled “ColorTemperature Shift Control for Dimmable AC LED Lighting,” Ser. No.61/234,094, which was filed by Z. Grajcar on Aug. 14, 2009, the entirecontents of which are incorporated herein by reference.

Examples of technology for improved power factor and reduced harmonicdistortion for color-shifting a light source are described withreference, for example, at least to FIGS. 20A-20C of U.S. ProvisionalPatent Application entitled “Reduction of Harmonic Distortion for LEDLoads,” Ser. No. 61/233,829, which was filed by Z. Grajcar on Aug. 14,2009, the entire contents of which are incorporated herein by reference.

Further embodiments of light engines for a lighting system are describedwith reference, for example, at least to FIGS. 1, 2, 5-5B, 7A-7B, and10A-10B of U.S. Provisional Patent Application entitled “Architecturefor High Power Factor and Low Harmonic Distortion LED Lighting,” Ser.No. 61/255,491, which was filed by Z. Grajcar on Oct. 28, 2009, theentire contents of which are incorporated herein by reference.

Various embodiments may incorporate one or more electrical interfacesfor making electrical connection from the lighting apparatus to anexcitation source. An example of an electrical interface that may beused in some embodiments of a downlight is disclosed in further detailwith reference, for example, at least to FIG. 1-3, or 5 of U.S. Designpatent application entitled “Lamp Assembly,” Ser. No. 29/342,578, whichwas filed by Z. Grajcar on Oct. 27, 2009, the entire contents of whichare incorporated herein by reference.

Instead of a threaded screw-type interface, some embodiments may includea section of a track lighting-style receptacle to receive the dual postinterface of an exemplary lamp. For example, a dual post electricalinterface of the type used for GU 10 style lamps may be used. An exampleof an electrical interface that may be used in some embodiments of adownlight is disclosed in further detail with reference, for example, atleast to FIG. 1, 2, 3, or 5 of U.S. Design patent application entitled“Lamp Assembly,” Ser. No. 29/342,575, which was filed by Z. Grajcar onOct. 27, 2009, the entire contents of which are incorporated herein byreference.

Some embodiments of a light apparatus may be integrated with packagingand/or thermal management hardware. Examples of thermal or otherelements that may be advantageously integrated with the embodimentsdescribed herein are described with reference, for example, to FIG. 15in U.S. Publ. Application 2009/0185373 A1, filed by Z. Grajcar on Nov.19, 2008, the entire contents of which are incorporated herein byreference.

A number of implementations have been described. Nevertheless, it willbe understood that various modification may be made. For example,advantageous results may be achieved if the steps of the disclosedtechniques were performed in a different sequence, or if components ofthe disclosed systems were combined in a different manner, or if thecomponents were supplemented with other components. Accordingly, otherimplementations are within the scope of the following claims.

The invention claimed is:
 1. A method of illuminating diurnal avianswith artificial light sources, the method comprising: supplying a firstlight having a first spectral content between 380 nm (nanometers) and780 nm to a substantially enclosed habitat for diurnal avians; supplyinga second light having a second spectral content between 380 nm and 780nm and having at least one local maximum in relative intensity at awavelength within 15 nm of a wavelength at which a predeterminedcharacteristic visual spectral response of the diurnal avian has a localmaximum to a substantially enclosed habitat for diurnal avians; andwherein at least one local maximum in relative intensity of the secondspectral content is above the median relative intensity of local maximaof the second spectral content.
 2. The method of claim 1, wherein the atleast one local maximum in relative intensity of the second spectralcontent is among the three highest relative intensities of local maximaof the second spectral content for wavelengths between 380 nm and 780nm.
 3. The method of claim 1, wherein the at least one local maximum inrelative intensity of the second spectral content is among the fourhighest relative intensities of local maxima of the second spectralcontent for wavelengths between 380 nm and 780 nm.
 4. The method ofclaim 1, wherein the first spectral content comprises a substantiallydifferent relative intensity characteristic than the second spectralcontent.
 5. The method of claim 1, wherein the at least one localmaximum in relative intensity of the second spectral content is between450 nm and 510 nm.
 6. The method of claim 1, wherein the at least onelocal maximum in relative intensity of the second spectral content isbetween 590 nm and 620 nm.
 7. The method of claim 1, wherein the atleast one local maximum in relative intensity of the second spectralcontent is below 400 nm.
 8. The method of claim 1, wherein the secondspectral content has at least one local maximum in relative intensity ata wavelength below 400 nm and that is within 15 nm of the wavelength atwhich a predetermined characteristic visual spectral response of thediurnal avian has a local maximum.
 9. The method of claim 1, wherein theat least one local maximum in relative intensity is at a wavelengthwithin about 10 nm of a wavelength at which the predeterminedcharacteristic visual spectral response of the diurnal avian has thelocal maximum.
 10. The method of claim 1, wherein the local maxima ofthe predetermined characteristic visual spectral response of the diurnalavian correspond to the spectral absorbance characteristics of oildroplets in the diurnal avian's eyes.
 11. The method of claim 1, whereinconverting the first light to a second light comprises emitting thesecond spectral content with a substantially red content in response tothe first spectral content comprising a substantially blue content. 12.The method of claim 1, wherein the second spectral content furthercomprises having at least two local maxima in relative intensity, eachlocal maxima being at a wavelength within about 25 nm of a first and asecond respective wavelengths at which the predetermined characteristicvisual spectral response of the diurnal avian has distinct local maxima.13. The method of claim 12, wherein the at least two local maxima inrelative intensity of the second spectral content are among the threehighest relative intensities of local maxima of the second spectralcontent for wavelengths between 380 nm and 780 nm.
 14. The method ofclaim 1, wherein the second spectral content further comprises having atleast three local maximum in relative intensity, each local maxima beingat a wavelength within about 30 nm of a first and a second respectivewavelengths at which the predetermined characteristic visual spectralresponse of the diurnal avian has distinct local maxima.
 15. The methodof claim 14, wherein the at least three local maxima in relativeintensity of the second spectral content are among the four highestrelative intensities of local maxima of the second spectral content forwavelengths between 380 nm and 780 nm.
 16. A spectrally adaptedillumination apparatus for illuminating diurnal avians, the apparatuscomprising: a first light source to generate a first light having afirst spectral content between 380 nm (nanometers) and 780 nm to asubstantially enclosed habitat for diurnal avians; a second light sourceto generate a second spectral content having at least one local maximumin relative intensity at a wavelength within 15 nm of a wavelength atwhich a predetermined characteristic visual spectral response of thediurnal avian has a local maximum to a substantially enclosed habitatfor diurnal avians; and, a conditioning circuit to selectively supplycurrent to both the first and second light sources.
 17. The apparatus ofclaim 16, wherein the at least one local maximum in relative intensityof the second spectral content is between 450 nm and 510 nm.
 18. Theapparatus of claim 16, wherein the at least one local maximum inrelative intensity of the second spectral content is between 590 nm and620 nm.
 19. The apparatus of claim 16, wherein the at least one localmaximum in relative intensity of the second spectral content is below400 nm.